You don't have to set the controllers to use an external NTP server. You can configure the environment to leverage the fuel-master as an NTP server. But you must configure that on the environment's settings page. By default, the environment's NTP servers are configured to use internet based servers. You are free to configure them to what ever you'd like, but you'll need to make sure that you configure the fuel-master's NTP server to make sure it can be queried by the controllers. Also network verification does not check NTP connectivity, only repository connectivity.
Anar,
You don't have to set the controllers to use an external NTP server. You can configure the environment to leverage the fuel-master as an NTP server. But you must configure that on the environment's settings page. By default, the environment's NTP servers are configured to use internet based servers. You are free to configure them to what ever you'd like, but you'll need to make sure that you configure the fuel-master's NTP server to make sure it can be queried by the controllers. Also network verification does not check NTP connectivity, only repository connectivity.